The Study
Comparison Between Shoulder Flexed and Extended Positions in Elbow Flexion Resistance Training on Regional Hypertrophy and Maximum Strength: Preacher versus Bayesian Cable Curls
This study compared two types of bicep curls in the same people, randomly assigning each arm to a different curl. It shows that both curls worked about the same for building muscle and strength in young men who don’t usually lift weights. But it doesn’t prove one is better for everyone or with other types of curls.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists wanted to see if doing bicep curls with your arm in front or behind your body makes a difference in muscle growth.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 547 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1This means you don’t need to worry about exact arm position during curls—both work equally well for building biceps.
- 2After 10 weeks, both arm positions led to about 6–9% bigger biceps and similar strength gains.
- 3No spot along the muscle grew more than others.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Sport Science
Year
2025
Authors
Parsa Attarieh, João Pedro Nunes, Saeed Khani, Saman Negahdar, Amirali Goli, Hamed Nazarirad, Shahriar Nazarirad, S. Mojtahedi, K. Nosaka, R. Soori
Related Content
Claims (8)
Just because a study doesn’t find a clear difference in arm muscle growth between two curl types, it doesn’t mean there isn’t a real difference — the study might just be too small to catch it.
Working your biceps with your arms stretched back might grow the upper part of the muscle a bit more than doing curls with your arms already in front of you.
If you're a guy new to lifting, doing bicep curls with your arms in front of you or behind you doesn’t really make a difference in how much your biceps grow — both ways work about the same.
If you're a young guy just starting out, doing bicep curls with your arms in front of you or behind you gives about the same strength gains after 10 weeks — even if one seems to improve a bit more, the difference isn’t really meaningful.
For guys new to lifting, doing bicep curls with your arms in front of your body works just as well for building arm muscle as doing them with your arms behind you — both give about the same 6% to 9% growth in 10 weeks.
Small studies might miss real differences just because they don’t have enough people in them — it’s like trying to hear a whisper in a noisy room.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.